This invention relates to closure plugs of a type that are retained in a threaded bore passing through the wall of the engine block which may connect into the water jacket of the block. Such closure plugs include a threaded nipple, an outwardly facing end portion having a diametric dimension greater than that of the nipple, and a sharp shoulder connecting the nipple and the end portion. In the prior art, a washer is disposed on the nipple for compression between the shoulder and the wall of the engine block surrounding the bore. The washer provides a sealing function to prevent the escape of engine coolant from the block, and a damping function, to reduce the transmission of vibration between the engine block and the closure plug closure plug which tends to loosen the seal across the interface.
The reliance upon a sealing washer is generally found to increase the installation time of the closure plug. In addition, the inadvertent loss of the sealing washer in the installation process can engender considerably increased costs to rectify the deficiency when it becomes apparent. Although it is well known to capture washers on screwed members, this tends to increase assembly costs of small assembly run items such as block closure plugs.
It is an object of my invention to provide washerless closure plugs for automotive engines.
It is another object of my invention to provide closure plugs for automotive engines that are more easily assembled into the automotive engine, with reduced margins for error.